Based on research by Joule, the environmental impact of Bitcoin mining accounts for 0.2% of global electricity consumption, and roughly the same CO2 emissions as Las Vegas. Many Bitcoin skeptics will describe mining as a "wasteful process" due to the enormous computing power required to solve increasingly difficult (and pointless) puzzles. However, this huge energy requirement is also what makes blockchains the most secure networks in the world. In order to add data to a blockchain, hackers would need to take over a large percentage of global energy production—which would be infeasible. The distribution of crypto mining is dominated by three major hardware producers: Bitmain, Canaan, and Ebang. There is a wide scale of mining operations worldwide—from students who steal electricity from their dorm room, to gamers who leverage their graphics cards to mine, to dedicated, large-scale crypto-mining farms (legal and illegal). Bitcoin mining requires an estimated 61.76 terawatt-hours (TWh) of electricity per year. By comparison, the Czech Republic uses 62.34TWh per year while Switzerland consumes 58.46TWh. If Bitcoin was a country, it would be the 41st most-energy-demanding nation in the world. Using some complicated math, Joule researchers estimate that this translates to 23MT (mega tonnes) of carbon dioxide, which is roughly 7% of the 30,000MT of energy-related emissions globally each year, but a very thin slice of total global emissions. If Bitcoin was a U.S. state, it pollutes as much as Kansas City. If Bitcoin was a U.S. city, it pollutes as much as Las Vegas. According to Union of Concerned Scientists (UCS), the top polluters in the world are China at 10.0GT (metric gigatons), United States at 5.41GT, India at 2.65GT, Russia at 1.71GT, and Japan at 1.16GT. The top polluters per capita are Saudi Arabia at 18.48T (metric tons), Kazakhstan at 17.60T, Australia at 16.92T, United States at 16.56T, and Canada at 15.32T. While the last thing we need right now is more negative pressure on global warming, Bitcoin mining is still a relatively small contributor to global emissions. You can donate to UCS research here.

Technology Review (June 12, 2019)